A few evenings ago I observed UGC 8058 (also known as Markarian 231), a galaxy in Ursa Major. It was easy to find only 1° north of epsilon UMa. With my 20" Dobsonian at 419x it looked very interesting with a bright stellar core and a diffuse, low surface brightness rest of the galaxy. On its northeast side, there was a "bay" that looked fainter than the main part. Please find attached my sketch.
This seems to be a very special galaxy, as some sources claim Markarian 231 is the closest quasar. But other sources claim it is a Seyfert galaxy. It makes me wonder what the exact difference is, because physically quasars and Seyfert galaxies are similar objects.
This paper describes it as a Seyfert galaxy, but also mentions that "Even without allowing for reddening the absolute visual magnitude of the Seyfert galaxy is Mv = -23.0 mag. If Av = 2.1 then M = -25.1 and Markarian 231 would have the optical luminosity of many quasars”:
So what exactly is the difference? According to this source “The distinction made in the literature between a quasar and a Seyfert 1 nucleus is largely morphological: in the latter a galactic envelope is seen whereas a quasar is generally star-like, without a nebulosity.”
But Brian Cudnik "Faint Objects and How to Observe Them", page 94, cites a table from Wikipedia (in the middle of the article under "Types of active galaxy"): https://en.wikipedia.org/wiki/Active_galactic_nucleus
So it seems that there is no definite distinction between Seyfert galaxies and quasars. There are many Seyfert galaxies easy to observe with smaller aperture (even Messier objects), but as far as I know other quasars than Markarian 231 can only be seen visually as point sources.
Is my latter statement correct? To those of you who use very large apertures, can you see host galaxies of any other quasars than Markarian 231? Or wouldn't you classify Markarian 231 as a quasar for that reason?
Clear skies,
Robin
Edit: Link was missing.
Last edited by Robin; April 4th, 2021 at 04:15 PM.
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